What is El Niño and How Does it Influence Snowfall in the United States?

24th April 2013 | Joel Gratz

El Nino generally forces the jet stream to take a more southern track from the Pacific Ocean through the U.S. This increases the chance of snow across the southern third of the county and increases the chance of warmer and drier weather across the northern third of the country. (Credit: NOAA)

Copyright: NOAA

Chris Farley popularized El Niño in a 1997 Saturday Night Live skit by dressing as a wizard and reciting lines like, “El Niño is Spanish for … the Niño” (trust me, it’s funnier when he says it). But it was 15 years earlier in the winter of 1982/1983 that El Niño first gained worldwide attention as it touched off severe flooding in Peru and California and droughts in Australia and Africa. Since El Niño can have a noticeable influence on weather around the world, let’s explore some science behind the phenomenon and translate its global effects to what American skiers really care about—snowfall across the U.S.

El Niño was the Peruvian name given to an abnormal warming of the oceans around Christmas time off the west coast of South America. Since this colloquial naming first took place, scientists have defined exactly what El Niño means to them: A warming of the ocean of more than 0.5 Degrees Celsius (about 1 Degree Fahrenheit) for three consecutive months in an area along the equator from the west coast of South America further west toward the central Pacific Ocean. Okay, that’s a mouthful of a definition, so simplify the details and think of it as a warming of the central Pacific Ocean.

The bigger question is not about what El Niño is or why it occurs but rather why do we care? We care because a large change in ocean temperature across a large area of ocean will cause changes in weather patterns across the globe. Remember, the entire earth system is linked together, so oceans, land areas, and the atmosphere all influence each other. Since the strength of El Niño (the warming of the ocean) peaks during the northern hemisphere fall, winter and early spring, the effects on weather from El Niño also peak during this time. Some of these effects include droughts across Australia, heavy rain over Peru and a change in the jet stream across North America which influences the location of the heaviest snow.

For the U.S., El Niño causes a stronger southern storm track that often brings higher than average snowfall to the southern third of the U.S. and less snow with warmer temperatures across the northern third of the U.S. For skiers, this often means that southern California, Arizona, New Mexico, and sometimes southern Utah and Colorado can see increased snowfall. There can also be cooler than normal weather across the southeastern U.S. that can help ski areas in Georgia, Alabama and North Carolina with their snow making efforts. Further, if things come together just right, some storms can track up the east coast and bring good amounts of snow to eastern areas of the Mid-Atlantic and New England.

However, and this is a BIG however, El Niño always comes in slightly different shades. We usually see an El Niño every couple of years, but the strength of El Niño changes each time, and so does its effects on worldwide weather. And El Niño is not the only climate phenomenon that can influence weather across the globe, so just looking at it will rarely allow meteorologists to accurately predict snowfall for the season ahead. Keep an eye on what scientists are predicting for El Niño and remember that it often means more snow across the southern third of the U.S. But also remember that each snowstorm has a mind of its own and you’ll be far better served looking for snow on the five-day forecast than betting on a three to six month snow forecast based on Chris Farley’s “the Niño”.

Meteorologist Joel Gratz is the creator of opensnow.com and is based in Boulder, Colo.